This invention relates generally to idlers used in various kinds of machinery and in particular, to an improved dead shaft idler.
For more than 100 years, dead shaft idlers have been manufactured with the same methods and materials. The two most common materials used are steel and aluminum. Methods for manufacturing are substantially the same for both. To fabricate a dead shaft idler, tubing is selected based on the needed outside diameter and the inside diameter (e.g., depending on speed and width). The tubing is cut to length, end plugs are installed, the outside diameter is machined to true it, and bearing bores are machined into the end plugs. The tube is then balanced as a last step. The balancing step is critical and is a labor intensive effort. Balancing requires the placement of weights, which often end up rolling loose in the center of the idler.
Because all kinds of conveying and converting systems utilize idlers, considerable attention has been given to improving their reliability, reducing bending of the tubing and reducing the inertial tension required to turn the idler. In web (i.e., continuous sheet) machinery, all kinds of materials, e.g., paper, plastic, tissue, foam, may be looped around a series of idler rollers. The idler rollers must have a necessary rigidity and strength to support a web load while withstanding the turning torque stress produced by the web. As noted previously, idler rollers have been made of steel, aluminum or other metals to provide the necessary rigidity and strength. Yet, the materials themselves have inherent problems. For example, steel rollers require excessive horsepower to overcome the initial start-up inertia and to keeping the steel rollers turning.
In many machines and systems, many different idlers of different lengths and diameters are needed. This requires extensive fabrication, costing substantial sums for labor and parts, as well as requiring a large inventory of tubing and bearing assemblies.
Many patents disclose idlers and methods of making thereof. For example, U.S. Pat. No. 1,742,454 issued to Van Derhoef and U.S. Pat. No. 2,593,069 issued to Steinmetz teach methods of making idler rollers. U.S. Pat. No. 1,622,758 issued to Beulke et al.; U.S. Pat. No. 2,808,730 issued to Shank; and U.S. Pat. No. 3,958,837 issued to Chagawa disclose improved roller designs. U.S. Pat. No. 4,029,200 issued to Dillon teaches a roller design fabricated in plastic. U.S. Pat. No. 5,022,132 issued to Valster et al. and U.S. Pat. No. 5,568,976 issued to Gabriele disclose bearing mounts for idlers. U.S. Pat. No. 5,387,962 issued to Castelli et al. discloses a self-aligning roll for belt loop modules.
Notwithstanding these known idlers and bearing mounts, the art has not adequately responded to date with the introduction of an idler which reduces job specific construction by eliminating end plugs, balancing weights, and extensive machining.